1. Field of the Invention
The present invention relates generally to tape cleaning devices used in tape libraries.
2. Description of Related Art
Magnetic tape is essentially a multiple layered ribbon generally comprising a substrate that supports a magnetic layer surface atop an under layer coating. The tape surface is lubricated to improve frictional robustness between the tape surface and a read/write head, which transfers data to and from the tape as the tape moves under the read/write head, the tape being wound between two reels. As the tape moves under the read/write head, an air bearing is created between the read/write head and the tape surface, thus creating an air gap, which in a perfect world induces consistent data pulses and essentially eliminates any wear between the tape and the read/write head.
Data is stored in the magnetic layer by way of retaining magnetic polarity changes (magnetic pulses) induced by the write element in a read/write head. As the tape traverses under the read/write head the pulses are sensed via the read sensor and with the use of a timer, the pulses are resolved as 1's and 0's known as digital data bits. The air gap created by the air bearing provides a consistent spacing between the read/write head and the tape to repeatedly write the digital data bits predictably.
In the real world, however, when the tape is read, occasional data bits are missing. This can be due to a variety of reasons including foreign material on the surface of the tape, which can interrupt the air bearing spacing, thus compromising a predictable data write or read. Examples of foreign material include particulate debris on the tape, smudge on the tape, oxide build-up due to micro-corrosion of the magnetic layer, etc. Recovery of the corrupt or missing data bits is commonly accomplished with error code detection and error code correction (ECC) schemes, which are mathematical predictions of expected data, such as a hash function or check-sum routine, for example. Likewise, extensive error rate detection can be an indicator that the spacing set up by the air bearing is compromised, perhaps due to a magnetic tape which has foreign material build-up. If foreign material build-up is the culprit to extensive error rate detections, restoring consistent spacing can, in some cases, solve the problem. Accordingly, the removal of foreign material build-up can be accomplished by way of tape cleaning techniques, such as wipe-downs, burnish heads or blades run over the surface of the tape. Such techniques are performed in clean room environments by dedicated independent machines.
It is to innovations related to this subject matter that the claimed invention is generally directed.